A toothache, also known as odontalgia or, less frequently, as odontalgy, is an aching pain in or around a tooth. In most cases toothaches are caused by problems in the tooth or jaw, such as cavities, gum disease, the emergence of wisdom teeth, a cracked tooth, infected dental pulp (necessitating root canal treatment or extraction of the tooth), jaw disease, or exposed tooth root. Causes of a toothache may also be a symptom of diseases of the heart, such as angina or a myocardial infarction, due to referred pain. After having one or more teeth extracted a condition known as dry socket can develop, leading to extreme pain. The severity of a toothache can range from a mild discomfort to excruciating pain, which can be experienced either chronically or sporadically. This pain can often be aggravated somewhat by chewing or by hot or cold temperatures. An oral examination complete with X-rays can help discover the cause. Severe pain may be considered a dental emergency.
A special condition is barodontalgia, a dental pain evoked upon changes in barometric pressure, in otherwise asymptomatic but diseased teeth.[1][2]
Atypical odontalgia is a form of toothache present in apparently normal teeth. The pain, generally dull, often moves from one tooth to another for a period of 4 months to several years. This is most commonly reported by middle-aged women. The cause of atypical odontalgia is not yet clear.

Toothaches are sometimes caused by an irritation of the pulp, known as pulpitis. This can be either reversible or irreversible. Irreversible pulpitis can be identified by sensitivity and pain lasting longer than fifteen seconds, although an exception to this may exist if the tooth has been recently operated on. Teeth affected by irreversible pulpitis will need either a root canal or an extraction.[3]